The Media Access Control (MAC) data communication protocol sub-layer is a sub-layer of the Data Link Layer (Layer 2) specified in the seven-layer OSI model. The Data Link Layer responds to service requests from the Network Layer (Layer 3) and issues service requests to the Physical Layer (Layer 1). The MAC provides addressing and channel access control mechanisms that make it possible for several terminals or network nodes to communicate within a multipoint network, typically a local area network (LAN) or wide area network (WAN). The MAC sub-layer acts as an interface between a Logical Link Control (LLC) sub-layer of the Data Link Layer and the network's physical layer. The MAC sub-layer emulates a full-duplex logical communication channel in a multipoint network. The MAC layer addressing mechanism is called a physical address or MAC address. The MAC address is a quasi-unique identifier assigned to each network adapter, making it possible to deliver data packets to a destination within a subnetwork, such as an Ethernet. An Internet Protocol (IP) address is a Network Layer that is assigned to communication devices in a computer network utilizing the Internet Protocol for communication between its nodes.